Transparent resin is used for various purposes including parts of consumer electronics, a food container, and general goods. Recently, from the viewpoint of light weight, productivity, and cost, transparent resin has been used frequently as a retardation film, a polarizing film protecting film, an antireflection film, a diffusion board, and a light guide plate; which are used in thin liquid crystal display for substituting cathode-ray tube TV monitors or optical parts of electroluminescence elements.
For optical application, methacrylic resin has been widely used. Here, methacrylic resin is superior in optical characteristics such as transparency and the like, however, it is inferior in heat resistance and the like, and thus the application of methacrylic resin was limited.
As the resin having improved heat resistance, a copolymer resin obtained by copolymerizing methyl methacrylate, Maleic anhydride, and styrene has been known (for example, Patent Literature 1).
In addition, a copolymer resin obtained by a copolymerizing aromatic vinyl monomer, meth(acrylic) acid ester monomer, and at least one of unsaturated dicarboxylic acid imide derivative and unsaturated dicarboxylic acid anhydride monomer (for example, Patent Literature 2).